This invention relates generally to the field of double-jacketed metal gaskets.
So far as known, the prior art method of forming circular double-jacketed metal gaskets has consisted of an extremely tedious and time-consuming job of making a circular double-jacketed gasket from a plurality of large metal sheets. Metal sheets for use in making double-jacketed gaskets typically have been purchased in rolls of 3 to 4 feet in width. Such gaskets are made in various diameters and widths, depending upon the equipment with which they are used. For large reactors or other equipment, gaskets often must be as large as 180 to 190 inches in diameter; thus, when the gasket diameter is larger than the sheet width, it has been necessary to weld together two or more sheets to form a single sheet for each side of the double-jacketed gasket. Hence, the number of welds or joint connections in a gasket has heretofore depending upon the width of the rolls of metal and the diameter of the desired gasket.
After the sheets have been prepared to the proper size for the diameter of the gasket to be made, a series of cutting steps have been employed to form the outer gasket ring of one width and an inner circular gasket liner of a lesser width. Each of such members has been cut from a single sheet formed as described above and each has been very narrow compared to the size of each sheet, resulting in 70% to 90% of the metal of each sheet being unused, and usually sold as scrap.
The final gasket itself has then been formed by hand positioning an intermediate ring or sections of asbestos between the outer gasket strip and the liner, and then crimping the outer ring over the inner liner.
The above-described prior art procedure is a tedious, time consuming operation that requires much hand labor. While certain machines have been designed to perform the steps of welding the plural sheets together and cutting out the circular gaskets, it has been necessary to still do many of such operations by hand. The large amounts of scrap material and the use of a great deal of hand labor has made the manufacture of each gasket very costly.